Mobility, defined as the ability to move independently from one point to another, emerges from the interaction of the individual with the environment. Mobility disability results when the individual is unable to meet the demands of the environment and thus restricts his or her mobility to smaller and smaller geographic ranges (i.e. immediate neighborhood, then their home, then one room in their home). Previous research examining mobility disability in older adults has focused primarily on factors within the individual such as weakness, pain, loss of motion, and co-morbidities that result in mobility disability. Little research has been done to explore the role of external factors, such as environmental features, on the emergence of mobility disability in older adults. This study has developed a tool to quantify the influence of specific environmental factors on the capacity for independent community mobility in older adults. An assessment protocol has been developed that examines the activities of older persons in their communities and evaluates actual activities done in the community. This protocol is being used to (a) identify critical environmental factors which contribute to mobility disability in older adults (for example which factors restrict individuals to their homes), (b) describe effective and ineffective strategies used by older adults to meet the demands of their community environment, and (c) develop mobility nomograms that can be used by clinicians to assess individual's mobility disability. Recent papers from assessmets done in two cities, Seattle, WA and Waterloo, Ontario have described the assessments.